Re: [ATM] Heat transfer

["Don Clement" <clement.focuser@verizon.net>]

> Silicone adhesives are optimized for gluing and/or sealing things
> NOT for transfering heat. If anything they are detrimental to
> rapid heat transfer.
>
You are right, in its pure form, RTV does not have high heat conductivity.
However if one adds copper or silver filings or aluminum oxide or BeO powder
to RTV, then is far more conductive. The advantage of heat conductive  RTV
is that one can cast a flexible heat conductive sheet or pad that can simply
be pressed against optics without having to bond to it or deal with messy,
migrating thermal grease. Have you ever tried to clean up silicon thermal
grease? Actually, silicon thermal grease is not especially thermally
conductive, but is more conductive that air. The idea is to use as thin a
layer of grease as possible ...just enough to exclude the air pockets
between non-flat surfaces. If surfaces were flat enough, then one would not
even need grease. Just wring together like gage blocks. But in the real
world, surfaces are seldom that flat.

Don Clement
Running Springs, California

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